1. Field of the Invention
The present invention relates to an electron-emitting device, an electron source, and an image-forming apparatus, and a method of driving the same.
2. Related Background Art
Surface conduction electron-emitting device is known as one of an electron-emitting device. A method of manufacturing the surface conduction electron-emitting device is disclosed in, Japanese Patent Application Laid-Open Nos. H08-264112, H08-321254, H10-228867, 2000-306500, 2001-319564, H01-279538, 2000-243225, H09-265900, 2000-311593, and 2000-030605. According to this manufacturing method, a “forming step” for forming a gap in a portion of an electroconductive film is performed. If necessary, a treatment called an “activation step” is further performed.
The “activation step” can be performed by repeatedly applying a pulse voltage to the electroconductive film on which the “forming step” has been completed in an atmosphere including a carbon-contained gas as in the case of the “forming step”. According to such a treatment, a carbon film made of carbon or a carbon compound derived from the carbon-contained gas present in the atmosphere is deposited in the gap formed by the “forming step” and in the vicinity of the gap. Therefore, a device current If and an emission current Ie significantly change, so that a more preferable electron-emitting characteristic can be obtained. Note that the device current If is a current flowing between a set of electrodes described later at the time when a voltage is applied between the set of electrodes. The emission current Ie indicates a current emitted from the electron-emitting device at the time when a voltage is applied between the set of electrodes.
FIGS. 2A and 2B are schematic views showing a structure of an electron-emitting device produced by the “activation step” disclosed in the above-mentioned patent documents. FIG. 2A is a plan view of the electron-emitting device. FIG. 2B is a cross sectional view along the line 2B-2B in FIG. 2A. In FIGS. 2A and 2B, reference numeral 1 denotes a substrate, 2 and 3 denote a set of electrodes opposed to each other, 4 denotes electroconductive films, 5 denotes a second gap, 6 denotes a carbon film, and 7 denotes a first gap. A voltage is applied between the set of electrodes 2 and 3; so that electrons are emitted from a region including the first gap 7 and its vicinity (electron-emitting region).
FIGS. 3A to 3D are schematic views showing an example of a process for manufacturing the electron-emitting device having the structure shown in FIGS. 2A and 2B.
Step (a)
First, the set of electrodes 2 and 3 are formed on the substrate 1 (FIG. 3A).
Step (b)
Subsequently, the electroconductive film 4 is formed to connect between the electrodes 2 and 3 (FIG. 3B).
Step (c)
The “forming step” for allowing a current to flow between the electrodes 2 and 3 is performed to form the second gap 5 in a portion of the electroconductive film 4 (FIG. 3C).
Step (d)
The “activation step” for applying a voltage between the electrodes 2 and 3 in an atmosphere containing a carbon compound gas is performed to form the carbon film 6 on the substrate 1 in the second gap 5 and on the electroconductive films 4 close to the gap 5, with the result that the electron-emitting device is produced (FIG. 3D).
The electron-emitting device manufactured by the above-mentioned treatments has an electron-emitting characteristic enough to use as an electron source applicable to an image-forming apparatus such as a flat panel display. Therefore, when a large area electron source plate in which a plurality of the above-mentioned electron-emitting devices are formed on the same substrate is manufactured, it is possible to realize, for example, a large area flat panel display (flat image display apparatus).